1. Field of the Invention
The present invention relates to a shoe press unit of a paper or cardboard machine for treatment of a fibrous pulp web in a press zone formed with an opposing surface and elongated in web run direction. The shoe press unit includes at least one press shoe, a flexible press belt guided over the press shoe, and at least one force element supported on a carrier. The at least one force element, which is formed by a cylinder/piston unit, presses the press belt against the opposing surface.
The present invention also relates to a method for tilting at least one press shoe in a press shoe unit for treatment of a fibrous pulp web in a press zone.
2. Discussion of Background Information
In known shoe press units, it is possible to predetermine an average, optimal distribution of pressure that is self-adjusting in the web run direction or to predetermine the adjustability of this pressure profile so that the pressing power can be altered over the length of the press zone with a same linear (line) force. In the latter case, the adjustability of the pressure profile is obtained, e.g., via a step-by-step displacement of the press shoe relative to a resultant force of the pressing; via a pressing of the shoe using two rows of pressing cylinders imparted with different pressures; or via introducing a torque moment without altering the line force, as discussed in German Patent Application No. DE 196 31 638.3.
However, these types of shoe press units have a number of disadvantages. For example, a practical need to change a pressure profile curve exists in only a very few cases. Thus, the advance expenditure for providing a tiltable (inclinable) press shoe arrangement is not even necessary with most applications of the shoe press roll. Further, the use of two rows of pressing cylinders imparted with different (differentiating) pressure can result in damage due to the more complex pressure control of both rows of cylinders. Imparting a tilt moment in the press shoe without altering the pressing force, e.g., in accordance with DE 196 31 638.3, is a better and more secure manner, however, the necessary expenditure is relatively high. Still further, a relatively large space within the press roll interior is lost due to the necessary elements for imparting the tilt on the press shoe. The elements in the roll interior are generally built or provided around a tilt lever so that a relatively large advance capital expenditure must be made if one seeks to expand a standardized construction to include the capability of tilting the press shoe.
The step-by-step displacement of the shoe relative to a level of the resulting force brings with it further disadvantages, e.g., that the levels are too large as a condition of the construction and that the machine must be turned off to displace the shoe. This results in a corresponding loss in production.